A lead-zinc smelting method and smelting system using coke and coal as fuel

Abstract

This invention discloses a lead-zinc smelting method and system using coke and coal as fuels. The method includes steps for zinc smelting in a closed blast furnace, and further includes a pulverized coal injection step: reducing the coke feed rate and decreasing the hourly coke feed amount; injecting pulverized coal from the tuyeres of the closed lead-zinc blast furnace into the furnace. This smelting method is capable of simultaneously producing metallic lead and metallic zinc. Based on the traditional ISP zinc smelting process, it replaces part of the coke with coal, reducing coke consumption and lowering smelting production costs.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal smelting technology, and in particular to a lead-zinc smelting method and system using coke and coal as fuel. Background Technology

[0002] Currently, there is only one smelting method in the world that can simultaneously produce metallic lead and zinc on a large scale: the closed blast furnace zinc smelting method, also known as ISP. The ISP zinc smelting process includes the following operations: A mixed lead-zinc ore or single concentrate, along with lead-zinc-rich miscellaneous materials (oxide materials), is sintered and roasted to produce intermediate sintered briquettes. These sintered briquettes and coke are then added to the closed blast furnace from the top, forming a material column of a certain height. High-temperature air at approximately 1000°C is then blown into the furnace from the bottom tuyeres, where it undergoes a vigorous physicochemical reaction with the coke and sintered briquettes. The generated zinc vapor, along with the furnace gas, enters the lead rain condenser from the top of the furnace, thus obtaining metallic zinc. The resulting slag and crude lead are discharged from the slag outlet at the bottom of the closed blast furnace. The ISP zinc smelting process uses only coke as fuel. Inside the furnace, the coke provides heat and a reducing atmosphere for the smelting reaction process and also acts as a framework for the material column, ensuring good permeability. Depending on the quality of the sintered blocks and coke, the coke yield in the furnace generally fluctuates between 34% and 42%. Traditional ISP zinc smelting processes rely solely on coke as fuel, excessively depending on high-quality metallurgical coke. However, coke prices are generally about twice that of coal, and high-quality metallurgical coke is even more expensive. In other words, traditional ISP smelting processes have extremely high energy costs, high production costs, and meager processing profits. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a lead-zinc smelting method using coke and coal as fuel.

[0004] The second objective of this invention is to provide a lead-zinc smelting system that uses coke and coal as fuel.

[0005] One of the objectives of this invention is achieved through the following technical solution:

[0006] A lead-zinc smelting method using coke and coal as fuel includes the steps of a closed blast furnace zinc smelting method (conventional ISP smelting process), and further includes the following steps:

[0007] Pulverized coal injection steps: reduce the coke rate into the furnace and reduce the amount of coke fed into the furnace per hour; inject pulverized coal into the lead-zinc closed blast furnace from the tuyeres.

[0008] In this invention, pulverized coal is injected into the lead-zinc closed blast furnace through a tuyer, causing it to burn in the tuyer area and the charge column, thereby replacing part of the coke. The closed blast furnace zinc smelting method (traditional ISP smelting process) includes the following steps: sintering agglomeration, formation of a charge column layer within the lead-zinc closed blast furnace, high-temperature air injection into the lead-zinc closed blast furnace, lead rain condensation, and discharge of slag and crude lead from the lead-zinc closed blast furnace. These operations are standard procedures in traditional ISP. This invention retains the traditional ISP process steps but innovatively adds pulverized coal injection, achieving the goal of replacing part of the coke with coal, reducing coke consumption, and lowering production costs.

[0009] As a preferred embodiment of the present invention, the specific operation in the pulverized coal injection step is as follows: The lead-zinc sealed blast furnace first performs full coke production. When the furnace reaches the material line, that is, when the material column in the furnace reaches the height of normal production, the furnace condition is normal. The material column period is h hours. When the material column in the lead-zinc sealed blast furnace reaches the height of normal production, at time h1, the material entering the furnace is located at the top of the material column. As normal production proceeds, the material entering the furnace moves downward with the material column and arrives at the tuyeres at time h2. The material column period h = (h2-h1) hours. When pulverized coal injection is prepared to start at a certain time H1, the coke rate entering the furnace is reduced, and the amount of coke entering the furnace per hour W1 is reduced. Starting from time H1, pulverized coal is injected into the lead-zinc sealed blast furnace at intervals of (h-1) hours. The amount of pulverized coal injected per hour = W1 / actual coal-to-coke replacement rate. Wherein, the actual coal-to-coke replacement rate = theoretical coal-to-coke replacement rate × 90%; the theoretical coal-to-coke replacement rate = Q 煤 / Q 焦 Q 煤 Q represents the calorific value of pulverized coal. 焦 The calorific value of coke is used. This invention takes into account that there is a certain escape of the injected pulverized coal, so the actual replacement rate will be slightly less than the theoretical coal-to-coke replacement rate. The actual replacement rate is calculated as 90% of the theoretical replacement rate.

[0010] In this invention, in the pulverized coal injection step, the phrase "reducing the coke rate entering the furnace and reducing the amount of coke entering the furnace per hour W1" refers to the reduction of the coke rate entering the furnace relative to the coke rate during full coke production. For example, if the coke rate during full coke production is 37%, and a pulverized coal injection operation is prepared to reduce the coke rate from 37% to 32%.

[0011] As a preferred embodiment of the present invention, the lead-zinc smelting method further includes a step of stopping pulverized coal injection. For example, when an abnormal furnace condition occurs or a sudden situation such as a pulverized coal supply interruption requires stopping pulverized coal injection, the stopping of pulverized coal injection includes two situations: emergency pulverized coal shutdown and planned pulverized coal shutdown. When an emergency pulverized coal shutdown is performed, if the lead-zinc enclosed blast furnace needs to be shut down urgently, the injection of pulverized coal into the lead-zinc enclosed blast furnace is immediately stopped. For example, emergency pulverized coal shutdown can be used when there is a sudden high or low voltage power outage or a major production failure (such as the main blower tripping, furnace shell burn-through, etc.).

[0012] When a planned coal shutdown is implemented, the lead-zinc sealed blast furnace continues production, the coke feed rate is increased, and the hourly coke feed is increased. Then, coal injection into the lead-zinc sealed blast furnace is stopped. The coal shutdown can be completed either entirely at once or in stages before feeding is stopped. For example, in the event of a general malfunction, if the lead-zinc sealed blast furnace can be shut down as planned, sufficient time can be allowed before feeding is stopped to cut off coal injection, thus completing the coal injection stoppage before feeding ceases.

[0013] As a preferred embodiment of the present invention, it is necessary to stop the pulverized coal injection operation, preferably by cutting off the pulverized coal injection before lowering the feed line. This is because as the height of the feed column decreases, the filtering effect of the feed column is weakened, increasing the escape of pulverized coal. The pulverized coal has too short a residence time in the furnace and escapes from the top of the furnace with the furnace gas before complete combustion, which is neither economical nor energy-efficient. Therefore, it is preferable to cut off the pulverized coal injection before lowering the feed line.

[0014] As a preferred embodiment of the present invention, when performing planned coal shutdown, the specific operation is as follows: when preparing to stop coal injection at a certain time H2, the coke ratio is appropriately increased, and the amount of coke fed into the furnace per hour is increased by W2, where W2 = amount of coal injected per hour × actual coal-coke replacement rate. Starting from time H2, after an interval of (h-1) hours, the injection of pulverized coal into the lead-zinc sealed blast furnace is stopped once or in stages.

[0015] As a preferred embodiment of the present invention, when the planned coal shutdown is a phased shutdown, the amount of coke fed into the furnace is adjusted in 2 to 3 steps, with each adjustment accounting for 8 to 15% of the total amount of coke, preferably 10%.

[0016] As a preferred embodiment of the present invention, when putting it into pulverized coal production, it can be done in one step or in two to three steps to adjust the amount of pulverized coal injected, with each adjustment amount accounting for about 10% of the total coke volume.

[0017] As a preferred embodiment of the present invention, when the amount of coal replacing coke reaches a certain value (for example, when the amount of coke fed into the furnace per hour is reduced to 20% or more of the amount of coke fed into the furnace per hour during full coke production), the lead-zinc closed blast furnace will experience insufficient temperature and inactivity in the tuyeres and hearth. To reduce such negative impacts and ensure that this smelting method can further improve the amount of coal replacing coke, an appropriate amount of oxygen enrichment should be added during the pulverized coal injection process in the lead-zinc closed blast furnace. Preferably, the lead-zinc smelting method of the present invention further includes an oxygen enrichment injection step, in which oxygen enrichment is continuously injected during the smelting process, and the oxygen enrichment is injected in the manner of Method 1 and Method 2.

[0018] Method 1: Directly add oxygen-enriched air into the cold air main pipe or hot air main pipe of the lead-zinc sealed blast furnace to increase the oxygen content of the air entering the furnace to 23-28%, preferably 25%.

[0019] Method 2: Using oxy-fuel lances to inject oxygen, with each lance injecting 100-200 Nm³ of oxygen. 3 / h; The oxygen-coal lance simultaneously injects oxygen and pulverized coal into the lead-zinc sealed blast furnace; The oxygen-coal lance is provided with an inner cavity for conveying pulverized coal and an outer cavity for conveying oxygen.

[0020] As a preferred embodiment of the present invention, in the pulverized coal injection step, without oxygen enrichment, the pulverized coal injection rate at a single tuyer is controlled at 150-180 kg / h; excessive amounts will increase runoff and are uneconomical. With sufficient oxygen enrichment, the pulverized coal injection rate at a single tuyer is controlled at 220-260 kg / h; excessive amounts will increase runoff and are uneconomical. Sufficient oxygen enrichment means that oxygen is continuously injected during the smelting process, and the methods of oxygen enrichment are described in Method 1 and Method 2. During pulverized coal injection, efforts should be made to ensure that all tuyeres inject pulverized coal, achieving broad and uniform injection.

[0021] In a preferred embodiment of the present invention, in the pulverized coal injection step, pulverized coal is injected using a pneumatic conveying method. The pulverized coal is transported from the pulverized coal silo to the furnace front distributor via a main pipe, and then transported to each tuyer of the lead-zinc sealed blast furnace via branch pipes of the furnace front distributor. Nitrogen or compressed air is used as the carrier, and the solid-to-gas ratio (i.e., pulverized coal conveying rate per hour / gas flow rate) is set to 10–20 (kg / Nm³). 3 If the solid-to-gas ratio is too small, the pulverized coal conveying process during dilute phase transport will cause severe erosion to the pipeline; if the solid-to-gas ratio is too large, the pulverized coal is prone to coking and clogging at the end of the spray gun due to insufficient cooling gas volume during dense phase transport, thus requiring a certain amount of cooling gas.

[0022] As a preferred embodiment of the present invention, the moisture content of the pulverized coal is less than or equal to 3% to ensure smooth transportation and prevent the pulverized coal from becoming too wet and caking in the pipeline.

[0023] As a preferred embodiment of the present invention, the particle size requirement of the pulverized coal is: the proportion of material under a 200-mesh sieve is greater than or equal to 80%. The smaller the particle size of the pulverized coal, the greater the specific surface area of ​​the pulverized coal and the greater the combustion reaction rate. However, considering the overall preparation cost, this particle size is more appropriate.

[0024] As a preferred embodiment of the present invention, the calorific value of the pulverized coal is greater than or equal to 23,000 J / g. The higher the calorific value, the more energy it provides. Considering the overall cost, the calorific value within the range mentioned above is more suitable.

[0025] In a preferred embodiment of the present invention, the pulverized coal is one or any combination of bituminous coal, anthracite, and coke powder; preferably, the pulverized coal is bituminous coal, or a combination of bituminous coal and anthracite, or a combination of bituminous coal and coke powder, or a combination of bituminous coal, anthracite, and coke powder. Bituminous coal increases the combustibility of the pulverized coal, while anthracite increases its calorific value and fixed carbon content. If the pulverized coal raw material includes coke undersize particles (coke powder), the amount of coke powder added should be reduced considering its poor grindability.

[0026] In a preferred embodiment of the present invention, after selecting the pulverized coal raw material, the pulverized coal raw material is ground into powder, then dried to obtain the finished pulverized coal. When the pulverized coal includes bituminous coal and anthracite, the weight ratio of bituminous coal to anthracite is (1-2):1, preferably 1:1. When the pulverized coal includes bituminous coal and coke powder, the weight ratio of bituminous coal to coke powder is (8:1) to (5:1). When the pulverized coal raw material is a combination of bituminous coal, anthracite, and coke powder, bituminous coal and anthracite can be the main components, with a small amount of coke powder added (preferably enough to consume the coke powder after daily coke screening).

[0027] As a preferred embodiment of the present invention, in the pulverized coal injection step, when the hourly coke feed rate is reduced to 20% or more of the hourly coke feed rate during full coke production, the height of the feed column is reduced or the thermal strength of the sinter is increased. When the coal-to-coke replacement rate reaches a certain proportion, and the coke feed rate is reduced by more than 20%, the proportion of coke in the feed column decreases significantly, the permeability of the feed column weakens, and the furnace pressure of the lead-zinc sealed blast furnace increases significantly. At this time, in order to appropriately reduce the furnace pressure and ensure that the main blower does not trip due to overpressure, the height of the feed column can be appropriately reduced or the thermal strength of the sinter can be appropriately increased. The softening point temperature of the sinter can be increased by increasing the CaO / SiO2 ratio of the sinter (e.g., close to the upper limit of 2.2), thereby increasing the thermal strength of the sinter and helping to alleviate the situation of excessive furnace pressure.

[0028] As a preferred embodiment of the present invention, in order to minimize the impact of pulverized coal injection on the original ISP process, the smelting method of the present invention can be operated according to the height of the raw material column. However, when the furnace pressure is too high, the furnace pressure can be reduced by appropriately lowering the height of the raw material column.

[0029] As a preferred embodiment of the present invention, the furnace pressure shall not exceed 45 kPa when producing coke, and shall not exceed 55 kPa when producing coal and coke at the same time.

[0030] The second objective of this invention is achieved by the following technical solution:

[0031] A lead-zinc smelting system using coke and coal as fuel includes a closed lead-zinc blast furnace, wherein a tuyer is provided at the lower part of the closed lead-zinc blast furnace, a tuyer water jacket is provided inside the tuyer water jacket, and a pulverized coal injection gun for injecting pulverized coal into the tuyer vortex zone of the closed lead-zinc blast furnace is installed inside the tuyer water jacket; the smelting system is used for any of the smelting methods described in the present invention.

[0032] As a preferred embodiment of the present invention, the tuyeres in the lead-zinc closed blast furnace are arranged in the same way as in the traditional ISP process, that is, the tuyer arrangement retains the current tuyer arrangement in the lead-zinc closed blast furnace of the ISP process, which can save on modification costs. Furthermore, during the smelting process, efforts are made to ensure that each tuyer is injected with pulverized coal, and that the injection volume at each tuyer is basically the same.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The lead-zinc smelting method using coke and coal as fuel provided by this invention is a smelting method that can simultaneously produce metallic lead and metallic zinc. Based on the traditional ISP zinc smelting process, it replaces part of the coke with coal, reducing the amount of coke used and lowering the smelting production cost. Since the smelting method provided by this invention does not change the original ISP production process, it is conducive to the promotion of the smelting method of this invention, making it easier for existing ISP production lines to be connected to the pulverized coal injection operation of this invention.

[0035] (2) The lead-zinc smelting method using coke and coal as fuel provided by the present invention can reduce the amount of coke entering the furnace by 12-20% without oxygen enrichment; and can reduce the amount of coke entering the furnace by 25-30% with sufficient oxygen enrichment, resulting in significant economic benefits.

[0036] (3) The lead-zinc smelting system using coke and coal as fuel provided by the present invention hardly needs to change the structure of the traditional ISP smelting system. Production can be achieved by simply adding some pulverized coal injection equipment, which can save on modification costs. Attached Figure Description

[0037] Figure 1 This is a process flow diagram of the lead-zinc smelting method using coke and coal as fuel provided in Embodiment 1 of the present invention. Detailed Implementation

[0038] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Unless otherwise specified, the raw materials, equipment, etc., used in the following embodiments can all be obtained by purchase.

[0039] Inductively coupled plasma (ISP) is a mature and efficient method that can simultaneously smelt lead and zinc. However, traditional ISP processes rely solely on coke as fuel, resulting in high production costs. This invention innovates and optimizes the ISP zinc smelting process, requiring almost no changes to traditional ISP operations. Only a small amount of additional equipment and some pulverized coal injection operations are needed to partially replace coke with coal. This invention reduces smelting energy costs by adjusting the energy structure of ISP, thereby saving on production costs.

[0040] Example 1

[0041] like Figure 1 As shown. Taking the lead-zinc closed blast furnace at Shaoguan Smelter as an example. The charge column height of the lead-zinc closed blast furnace at Shaoguan Smelter is 6m, the charge column period is about 2.5h, and the coke yield is 35-42%.

[0042] A lead-zinc smelting method using coke and coal as fuel includes the steps of a conventional closed blast furnace zinc smelting method (ISP process). First, sintered blocks are prepared. The sintered blocks and coke are fed into a lead-zinc closed blast furnace to form a charge column. The zinc vapor generated during smelting in the furnace enters a lead rain condenser to obtain metallic zinc. The generated slag and crude lead are discharged from the slag outlet at the bottom of the lead-zinc closed blast furnace. Example 1 is an improved ISP process. At a certain point in the coking process, the coke yield is reduced, the amount of coke fed into the furnace is decreased, and pulverized coal injection is initiated, as detailed below:

[0043] Pulverized coal is transported from the pulverized coal bunker to the furnace front distributor via a main pipe using pneumatic conveying. From there, the pulverized coal is distributed to each tuyer of the lead-zinc sealed blast furnace via branch pipes of the furnace front distributor. Nitrogen is used as the carrier gas in this pneumatic conveying system, with a solid-to-gas ratio (pulverized coal conveying rate / gas flow rate) of 15 kg / Nm³. 3 The coal injection rate at a single air outlet is controlled at 160-170 kg / h.

[0044] Table 1 Composition of Sintered Blocks

[0045] Pb% Zn% S％ Cd% Sb% As% <![CDATA[SiO2%]]> <![CDATA[CaO / SiO2]]> <![CDATA[Pb+SiO2]]> 15～21 36～42 <1 ≤0.2 0.15～0.25 <0.40 <4.5 1.4～2.2 ≤26

[0046] The lower heating value Q of coke 焦 Approximately 27,000 J / g;

[0047] The lower heating value Q of a mixture of bituminous coal and coke powder in a 7:1 ratio 煤 24030 J / g;

[0048] Theoretical coal-to-coke replacement rate = Q 煤 / Q 焦 =24030 / 27000=0.89,

[0049] Actual replacement rate = Theoretical coal-to-coke replacement rate × 90% ≈ 0.8.

[0050] The lead-zinc closed blast furnace at Shaoguan Smelter has a charge column height of 6m and a charge column period of approximately 2.5 hours. On a certain day, during full coke production, the coke ratio was 37%, and the weight of each batch of sintered lump material fed into the furnace was approximately 5200kg. With 6 batches fed per hour, the hourly coke weight fed into the furnace was 5200 × 6 × 0.37 = 11544kg. At 10:00 AM, preparations for pulverized coal injection were made to reduce the coke ratio from 37% to 32%, thus reducing the hourly coke feed by 5200 × 6 × 5% = 1560kg. At 11:30 AM, the pulverized coal injection device was started, with a set injection rate of 1560 ÷ 0.8 = 1950kg / h. If production remained stable for about 2 hours at this coal and coke consumption, and if the slag fluidity, slag zinc content, and furnace pressure were all within normal ranges, further replacement could be continued, or no further replacement could be chosen.

[0051] If a common malfunction necessitates a shutdown of the feed line (a shutdown of the feed line means ceasing all feeding into the lead-zinc enclosed blast furnace, consuming the existing 6m column of material, or at least most of it, and then ceasing production), then the pulverized coal injection must be cut off before stopping feeding. Assuming preparations for cutting off the pulverized coal injection begin at 2 PM, reducing the coke ratio from 32% to 37%, then the hourly increase in coke input is 5200 × 6 × 5% = 1560 kg. The pulverized coal injection unit is stopped at 3:30 PM, after which the feed line is operated as a standard ISP feed line.

[0052] Example 1: Cutting off the pulverized coal injection before the feed line (cutting off the pulverized coal injection before lowering the feed line) can save costs and is both economical and environmentally friendly. This is because as the height of the feed column decreases, the filtering effect of the feed column is weakened, which increases the escape of pulverized coal. The residence time of pulverized coal in the furnace is too short, and it escapes from the top of the furnace with the furnace gas before it is completely burned, which is neither economical nor energy-saving.

[0053] The smelting method according to Example 1 yields the following results: After pulverized coal injection, the amount of coke used is reduced by 1560 / 11544 = 13.51%. The price of bituminous coal is generally only half that of coke, while the coal-to-coke replacement rate is only 0.8, meaning that 1000 kg of pulverized coal in the furnace has the same effect as 800 kg of coke, thus resulting in significant energy cost savings.

[0054] Example 2

[0055] The difference between Example 2 and Example 1 is that during the production process, oxygen enrichment is added, and the amount of coke entering the furnace is reduced by 25-30%. The pulverized coal injection rate at a single tuyer is controlled at 220-260 kg / h.

[0056] Example 3

[0057] The difference between Example 3 and Example 1 is that during the pulverized coal injection stop operation, the amount of coke fed into the furnace is adjusted in two steps, with each adjustment accounting for 10% of the total amount of coke.

[0058] Example 4

[0059] The difference between Example 3 and Example 1 is that when putting it into pulverized coal production, the amount of pulverized coal injected can also be adjusted in two steps, with each adjustment amount accounting for about 10% of the total coke volume.

[0060] Example 5

[0061] The difference between Example 5 and Example 1 is that the amount of coke fed into the furnace per hour is reduced to 20% of the amount of coke fed into the furnace per hour during full coke production, and the excessive furnace pressure is alleviated by reducing the height of the feed column.

[0062] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A lead-zinc smelting method using coke and coal as fuel, comprising the step of a closed blast furnace zinc smelting method, characterized in that, It also includes the following steps: Pulverized coal injection procedure: Reduce the coke rate entering the furnace and decrease the amount of coke entering the furnace per hour; inject pulverized coal into the lead-zinc sealed blast furnace from the tuyeres, as follows: The lead-zinc closed blast furnace first produces coke, with a material column period of h hours. When it is ready to start pulverized coal production at a certain moment H1, the coke rate is reduced and the amount of coke fed into the furnace per hour W1 is reduced. Starting from moment H1, pulverized coal is injected into the lead-zinc closed blast furnace at intervals of (h-1) hours. The amount of pulverized coal injected per hour = W1 / actual coal-coke replacement rate. Wherein, the actual coal-to-coke replacement rate = theoretical coal-to-coke replacement rate × 90%; the theoretical coal-to-coke replacement rate = Q 煤 / Q 焦 Q 煤 Q represents the calorific value of pulverized coal. 焦 This refers to the calorific value of coke. The material column period is as follows: when the material column in the lead-zinc sealed blast furnace reaches the height of normal production, the material entering the furnace is located at the top of the material column at time h1. As normal production proceeds, the material entering the furnace moves downward with the material column and arrives at the tuyeres at time h2. The material column period h = (h2 - h1) hours.

2. The lead-zinc smelting method using coke and coal as fuel as described in claim 1, characterized in that, It also includes a coal injection cessation step, which includes two situations: emergency coal injection cessation and planned coal injection cessation. When an emergency coal injection is carried out, the lead-zinc sealed blast furnace will immediately stop injecting pulverized coal into the lead-zinc sealed blast furnace when it stops production. When a planned coal shutdown is carried out, the lead-zinc sealed blast furnace continues production, the coke feed rate is increased, the hourly coke feed is increased, and then the coal injection into the lead-zinc sealed blast furnace is stopped. The coal shutdown is completed in one go or in stages before the feeding stops.

3. The lead-zinc smelting method using coke and coal as fuel as described in claim 2, characterized in that, When a planned coal shutdown is carried out, the specific operation is as follows: When it is time H2 to stop coal injection, the coke rate is increased and the amount of coke fed into the furnace per hour is increased by W2. W2 = amount of coal injected per hour × actual coal-coke replacement rate. Starting from time H2, after an interval of (h-1) hours, the injection of pulverized coal into the lead-zinc sealed blast furnace is stopped once or in stages. When the planned coal shutdown is a phased shutdown, the amount of coke fed into the furnace is adjusted in 2 to 3 steps, with each adjustment accounting for 8 to 15% of the total amount of coke.

4. The lead-zinc smelting method using coke and coal as fuel as described in claim 1, characterized in that, It also includes an oxygen-enriched injection step, in which oxygen is continuously injected during the smelting process. The methods of injecting oxygen include Method 1 and Method 2. Method 1: Directly add oxygen-enriched air into the cold air main or hot air main of the lead-zinc sealed blast furnace to increase the oxygen content of the air entering the furnace to 23-28%; Method 2: Using oxy-fuel lances to inject oxygen, with each lance injecting 100-200 Nm³ of oxygen. 3 / h; The oxygen lance simultaneously injects oxygen and pulverized coal into the lead-zinc sealed blast furnace.

5. The lead-zinc smelting method using coke and coal as fuel as described in claim 1, characterized in that, In the pulverized coal injection step, without oxygen supplementation, the pulverized coal injection rate at a single tuyer is controlled at 150-180 kg / h; with sufficient oxygen supplementation, the pulverized coal injection rate at a single tuyer is controlled at 220-260 kg / h.

6. The lead-zinc smelting method using coke and coal as fuel as described in claim 1, characterized in that, In the pulverized coal injection step, pulverized coal is injected using a pneumatic conveying method, with nitrogen or compressed air as the carrier, and the solid-to-gas ratio is set to 10–20 kg / Nm³. 3 .

7. The lead-zinc smelting method using coke and coal as fuel as described in claim 1, characterized in that, The pulverized coal has a moisture content of less than or equal to 3%, a sieve undersize ratio of greater than or equal to 80%, and a calorific value of greater than or equal to 23,000 J / g. The pulverized coal is one or more of bituminous coal, anthracite, and coke powder.

8. The lead-zinc smelting method using coke and coal as fuel as described in claim 7, characterized in that, The pulverized coal is bituminous coal, or a combination of bituminous coal and anthracite, or a combination of bituminous coal and coke powder, or a combination of bituminous coal, anthracite and coke powder.

9. The lead-zinc smelting method using coke and coal as fuel as described in claim 7, characterized in that, When the pulverized coal includes bituminous coal and anthracite, the weight ratio of bituminous coal to anthracite is (1-2):1; when the pulverized coal includes bituminous coal and coke powder, the weight ratio of bituminous coal to coke powder is (8:1) to (5:1).

10. The lead-zinc smelting method using coke and coal as fuel as described in claim 1, characterized in that, In the pulverized coal injection step, when the amount of coke fed into the furnace per hour is reduced to 20% or more of the amount of coke fed into the furnace per hour during full coke production, the height of the feed column is reduced or the thermal strength of the sintered blocks is increased.

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